The present invention relates to dental air and water line purification assemblies and, in particular, to manifold assemblies which support disposable disinfectant cartridges to a variety of dental hand tools, such as air-powered, high speed handpieces, air-water syringes and scalers. Alternative constructions integrate the cartridge manifolds into hand tool adaptors, hand tool handles or discharge tips.
The presence of microorganisms within dental unit water lines (DUWL) has been documented in medical and dental literature and discussed at related symposia. Studies have confirmed the presence of varieties of bacterium, viruses and protozoa at nutrient rich biofilms that form over time on the tubing walls of the water supply lines that feed hand tools of dental and medical practitioners. Biofilms also exist within the flow channels of the hand tools. Such microorganisms can include non-pathogenic microbes, as well as pathogenic microbes.
The microbes can be admitted to the water lines and hand tools from municipal water supplies and the patients being treated. The later contamination occurs with backflow conditions that exist during typical patient treatments and the use of conventional hand tools. Backflow or passive retraction arises for a variety of reasons such as laminar flow, eddy currents, vortexes, and venturi effects within the hand tool and associated tubings which draw microorganisms that are present in the moisture laden working space into the water and air lines.
Although most practitioners commonly employ procedures to periodically flush the water lines at the start of a week, with the beginning of each day, and/or between patients, the involved fluid mechanics principally remove only loosely attached microbes which may form between flushings. During normal use, a laminar flow at the walls, otherwise, provides a stationary flow condition, which does not particularly affect the growing microbes. Microbe concentrations of 1.times.10.sup.7 per ml have been observed in sampled water from DUWL's.
Decontamination efforts directed to minimize and contain the potential health risks represented by microbial colonies dwelling in most DUWL's have included attempts to flush chemical disinfectants through the DUWL; sterilize selected hand tool components (e.g. by autoclaving), including the DUWL; mount anti-retraction systems or check valves into the DUWL to prevent backflow; and use unit dose, sterilized and/or distilled water or saline packs with each patient.
The problem and some of the foregoing attempts to find solutions to contain the problem are discussed in the following articles: "Dental Unit Water Lines", K. Scarbeck, AGD Impact, pp. 3, 6-12, November, 1993; "Microbial Contamination of Dental Unit Water Lines-Prevalence," Intensity and Microbiological Characteristics", JF. Williams et al, JADA, Vol. 124, pp. 5-65 (October 1993); "Expanding the Bubble", L. H. Meskin, JADA, Vol. 124, pp. 9-12 (October 1993); and "Dental Unit Water Lines Under Review--ADA Workshop Looking at Ways to Limit Bacterial Presence", J. Jakush, ADA News, pp. 14, 15 (Sep. 20, 1993).
NASA has considered the problem with respect to space travel. Various commercial vendors of water treatment chemicals also provide different assemblies and packaging arrangements of disinfectants to treat water at the point of entry to a building or water supply fixture.
Water purification assemblies for single and multi-patient treatment stations are also known. Such assemblies are sold by Ecomaster Corporation, St. Paul, Minn. and include cartridge based filtration materials and multi-valent iodine resin bactericides and virucides for purifying relatively large volumes of water supplied to medical and dental treatment stations. Although the latter assemblies minimize contaminants introduced from a water supply source, microbial growth and biofilms can still exist in the conduits intermediate the treatment assembly and the hand tools contacting the patient.
Various devices are also known which mount to the tubing sections of the DUWL. U.S. Pat. No. 5,204,004 discloses a microporous membrane filter and assembly for retaining a microbe filter to the DUWL tubing. U.S. Pat. No. 5,230,624 discloses an iodinated cartridge that includes a single bed of disinfectant media and couples to the DUWL tubing to admit a residual amount of disinfectant to liquid passing through the tubing.
In appreciation of the foregoing problems and limitations of existing water and air disinfectant devices, the present invention provides alternative mechanisms for treating or purifying the water and air that contacts a dental or medical patient directly at a discharge port of a hand tool or as close as physically possible to the discharge port. The viability of such treatment devices has been confirmed in studies of water periodically sampled from hand tools equipped with the invention.